Separable filter housing and cartridge for a fluid flow line

ABSTRACT

A filter unit for use in filtering fluids and especially gases including compressed air to remove contaminants therefrom and comprising a pair of similar transparent cup-shaped housing members defining a cylindrical cavity which receives a filter cartridge filled with pulverent filter material enclosed in a sheath formed from porous textile material.

151 3,681,899 51 Aug. 8, 1972 [56] References Cited UNITED STATESPATENTS CARTRIDGE FOR A FLUID FLOW LINE [72] Inventor:

United States Patent Grote [54] SEPARABLE FILTER HOUSING AND 2,079,3075/1937 Kehl Gum 3,291,126 12/1966 Messick [73] Assignee: National Bankand 'hust Company 3,483,677 12/1969 Pinto.

of Central Pennsylvania, Adminls- 3,555,787 1/1971 Lustig...

Primary Examiner-Arthur D. Kellogg Attorney-C. Hercus Just nantstherefrom and comprising a pair of similar transparent cup-shapedhousing members defining a cylindrical cavity which receives a filtercartridge filled with pulverent filter material enclosed in a sheathformed from porous textile material.

trator, d.b.n.c.t.a. o1 Willard C. Beach deceased and Administratorc.t.a. of the Estate of Mary B. Beach, Hanover, Pa.

[22] Filed: July 9, I970 [21] Appl. No.: 53,475

[52] US. Cl. ....S5/503, 55/475, 551509, 55/515, 55/518 [51] Int. Cl.39/08 [58] Field of Seerch........55l5l5, 578, 480, 475, 522, 55/503,509

PATENTED 819?? 3,681,899

sum 10F 2 INVENTOR. GEORGE A. GROTE ATTdNEY SEPARABLE FILTER HOUSING ANDCARTRIDGE FOR A FLUID FLOW LINE CROSS-REFERENCE TO RELATED APPLICATIONThe present invention comprises a filter unit embodying certain of thebasic principles of the invention comprising the subject matter ofpatent application Ser. No. 37,125, filed May 14, I970.

BACKGROUND OF THE INVENTION Many types of filter units have been devisedheretofore for purposes of filtering various types of fluids, such asgases, including compressed air, and in which various filter materialscomprising steel wool, rock or slag wool, cotton masses, and the like,are employed as filtering means. Various types of metallic housings havebeen used to contain the filtering media. Inasmuch as various gaseswhich require filtering are corrosive to certain types of metal and alsocertain presently used types of filtering media, such previously devisedfilter units are not satisfactory, especially when filtering corrosivetypes of gases.

Particularly from an efficiency standpoint, very little attention hasbeen given heretofore to matters of providing filtering media which iscontained in a housing in such manner that by-passing of the filteringmedia by at least a certain amount of the gases can not occur, dueparticularly to the structure of the housing and the manner in which thefiltering media is contained therein.

Typical examples of filtering media devised heretofore are illustratedin US. Pat. No. 2,400,719, Stackhouse, dated May 21, 1946 and US. Pat.No. 2,789,654, to Zurit, dated Apr. 23, 1957. The Stackhouse structureutilizes compressed rock wool disposed between a pair of screenscontained in a brass chamber which is closed at one end by a brass plug.Brass is readily attacked by certain corrosive gases. Further, it isdifficult to inspect, at least visually, the condition of the filtermedia within a metallic enclosure, particularly in the absence of anytransparent panels or other means by which such observation may be made.

The Zurit structure shows a filter housing containing a cartridgecontaining activated carbon enclosed in a polyethylene tube for purposesof filtering air being delivered to beer kegs. No special sealing meansare referred to in the disclosure which would prevent the by-passing ofthe air or at least portions of it between opposite ends of the housingso as to escape filtering. While no specific description is set forth inthe specification of said patent, it would appear that the housing andthe elements directly connected thereto are formed from metal and thuspreclude visual inspection of the condition of the cartridge within thehousing.

SUMMARY OF THE INVENTION The present invention comprises a filter unitespecially adapted for filtering, in particular, gaseous material,including air, and comprises a housing formed from a pair of similarcup-shaped members each formed from synthetic resin material andconnected at one end of each of the members by complementary internaland external threads, the members defining a cylindrical cavity ofprecise configurations and dimensions and the opposite ends of thehousing members being constricted to form seats against which perforateddiscs are disposed to engage the opposite ends of a cylindrical filtercartridge comprising a flexible sheath formed from textile material andincluding end discs which are connected by stitching to the oppositeends of a seamless cylindrical sleeve, said cartridge being filled withpulverent filter material and the length and diameter of the cartridgerespectively being slightly greater than the distance between theperforated discs within the housing and the diameter of the cavitytherein, whereby pressure is exerted upon the pulverent material withinthe cartridge when positioned operatively within the cavity of thehousing so as to force the cylindrical sleeve of the cartridge intocontinuous circumferential contact with the surface of the cavity withinthe housing and thereby prevent bypassing of any gases between saidcartridge and cavity walls.

Another object of the invention is to form the cupshaped housingmembers, by molding, from transparent synthetic resin material so as toprovide ready visual inspection of the condition of the filter cartridgewithin the housing and also provide a housing which is not susceptibleto chemical reaction by most gases and especially corrosive type gasesto be filtered by said unit.

A further object of the invention is to provide a filter cartridge inwhich the sheath which encloses the pulverent filter material preferablyis formed from thermoplastic synthetic resin filaments and a seamlesstube thereof forms the sidewalls of the cartridge and is connected toend discs of the same material by stitches forming sear-m which aredisposed in various ways to prevent sifting of the pulverent filtermaterial from the ends of the cartridge incident to fluids, andespecially gases, passing therethrough.

Details of the foregoing objects and of the invention, as well as otherobjects thereof are set forth in the following specification andillustrated in the accompanying drawings comprising a part thereof.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a filter unitembodying the principles of the present invention.

FIG. 2 is a top plan view of the filter unit shown in FIG. 1.

FIG. 3 is a longitudinal sectional view of an exemplary cartridgeadapted to be enclosed within the housing of the unit shown in FIGS. 1and 2.

FIG. 4 is a fragmentary enlarged transverse sectional view of the upperand discharge end portion of the cartridge shown in FIG. 3, the samebeing broken intermediately of the opposite sides thereof to foreshortenthe view.

FIG. 5 is a view similar to FIG. 4 but illustrating the lower, inlet endof the cartridge shown in FIG. 3.

FIG. 6 is a longitudinal sectional view of the housing of the unitillustrated in FIGS. 1 and 2 to show details thereof.

FIG. 7 is a plan view of the perforated discs respectively disposed inopposite ends of the housing of the filter unit shown in FIG. 6.

FIG. 8 is a plan view of a gasket inserted between the two elements ofthe housing of the filter unit shown in FIG. 6.

FIG. 9 is a fragmentary longitudinal sectional view, on a larger scalethan in the preceding figures, and illustrating the manner in which theseamed discharge end of the cartridge illustrated in FIG. 4 is disposedwhen mounted within the filter housing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention primarilycomprises an improvement over applicant's prior application, Ser. No.37,125, referred to above, to the extent that the housing of the unitcomprising the subject matter of said previous application is notreadily adaptable to being manufactured in small sizes. Further,particularly since the housing thereof is formed from cast metal memberswhich are connected to the opposite ends of a transparent cylindricalrigid tube, it is necessary to plate said castings with suitable metalsto render the same reasonably non-reactive to certain corrosive types ofgases intended to be filtered by the unit.

In general, while the cost of said housing member is warranted in largersizes of capacities of filter units, when adapted to smaller sizes, thecost of such production is not competitive with other filtersmanufactured by different producers. Accordingly, the principal purposeof the present invention is to provide a housing which preferably iscast from synthetic resins and particularly those which, whenmanufactured into a housing for a filter unit render the same reasonablynonreactive to most types of gases intended to be filtered thereby. Inaddition, the cost of production is minimal without sacrificingstructural advantages, whereby a filter unit embodying the principles ofthe present invention may be manufactured at a cost which is highlycompetitive with filters of other producers and such housings may be inrelatively small sizes as well as larger ones.

Referring to FIGS. 1 and 6, the housing 10 comprises a pair of similarcup-shaped housing members 12 and 14 which preferably are formed bymolding. The preferred materials are suitable synthetic resins whichproduce rigid molded members capable of retaining precise shape anddimensions. One such resin that is especially adapted for this is apolycarbonate such as a condensate product of bisphenol A and phosgene,one commercial brand of which is manufactured by the General ElectricCompany, identified as No. 14-] l l, and sold under the trade nameLEXAN. Other resins having similar physical characteristics may be used,whereby the specifically identified resin is primarily indicated forpurposes of illustration rather than restrictron.

The member 12 is provided on one end with an enlargement 16 havinginternal threads which are complementary to external threads formed onone end of housing member 14 as clearly shown in FIG. 6. The terminalend of said externally threaded end of member 14 abuts a gasket 18, ofrelatively compressible material such as neoprene. The thickness of thegasket is adequate to effect an air-tight seal between the threaded endsof the members 12 and 14 when tightly connected together.

The ends of the members 12 and 14 which are opposite the threadablyconnected ends are constricted respectively to form seats 20 and 22within planes which are transverse to the longitudinal axis of thehousing 10 and against which perforated discs 24 abut. Said discspreferably are formed from stainless steel screening of suitable meshand relatively rigid for purposes to be described. A plan view of anexemplary disc 24 is shown in FIG. 7 and the position of the samerelative to seats and 22 are shown in FIG. 6.

The constricted ends 26 and 28 respectively of members l2 and 14 areprovided with axial passages 30 and 32 of materially smaller diametersthan the interior of the members 12 and 14. Said constricted ends 26 and28 are provided with means to connect the same respectively to conduitsby which fluids, including gases and especially air, are delivered toand withdrawn from the housing 10 in the manner indicated by thedirectional arrows in FIG. I. In the specific illustration shown inFIGS. 1, 2 and 6, said connecting means comprise external pipe threads34 but other forms of connecting means may be employed if desired.Further, ad-

20 jacent the threads 34, the constricted ends 26 and 28 also preferablyare formed exteriorly to provide a suitable geometric configuration incross-section, such as the square 36 shown in FIG. 2. Other alternativeconfigurations may be used.

The inner walls of the housing members 12 and 14 preferably arecylindrical and of identical uniform diameters, whereby the combinedinterior surfaces of said members define an interior cylindrical cavity38 which is of a precise uniform diameter throughout its length which isdefined by the distance between the perforated discs 24. By way ofillustration of the adaptability of the design of the housing 10 for usein filters of relatively small size, the illustration in FIG. 6 issubstantially full scale for one exemplary size of filter. The interiorcavity 38 is approximately two inches in diameter and six inches inlength. If desired, the diameter and length may be made smaller orlarger, as desired.

One of the members, such as member 12, is provided with mounting means40 which, as shown in FIG. 2 in particular, is disposed slightlylaterally to enlargement 16 of member 12 at its outer surface 42, so asreadily to adapt the same for attachment to a supporting surface, suchas a wall or other suitable surface. Especially in view of the fact thatthe member 12 is provided with the enlargement l6 and the outer surface42 of the supporting means 40 is laterally offset from the periphery ofthe enlargement 16, the member 14 easily can be unscrewed from member 12while the latter remains mounted in operative position for purposes ofremoving a filter cartridge from or installing the same within thecavity 38.

The members 12 and 14 preferably are molded from synthetic resin whichis transparent, whereby the condition of the filter cartridge within thecavity 38 readily may be visually inspected. Preferably, as is describedin detail hereinafter, the cartridge is of such type that, for example,the color of the same progressively changes as it is subjected tocontinuous filtering operations so that when the color of the cartridgechanges for its full length, such change in color serves as anindication that the cartridge should be replaced. Such phenomenon isdescribed primarily for purposes of illustration rather thanrestriction, however.

An exemplary filter cartridge 44 of the type preferably intended for usewithin the cavity 38 is illustrated in longitudinal sectional view inFIG. 3. Various details thereof are also shown in FIGS. 4, 5 and 9. Thefilter cartridge 44 comprises a completely enclosing sheath whichincludes a seamless cylindrical sleeve 46 formed from textile fabricwoven or otherwise prepared preferably from thermoplastic syntheticresin filaments, such as a suitable polyamide, one form of which is soldunder the trademark NYLON. Such fabric is relatively inert to air andmost forms of gases and particularly corrosive gases. Other kinds andtypes of thermoplastic synthetic resin fabrics which are similarlynon-reactive to air and most forms of gases may be used in lieu ofNYLON, if desired. The mesh of the fabric from which the sleeve 46 iswoven is relatively fine, so as to minimize sifting of the pulverentfilter material 48, suitable types of which comprise diatomaceous earthor fullers earth, for example.

Opposite ends of a suitable length of the seamless cylindrical sleeve 46are connected to and closed by discs 50 and 52 which preferably arefonned from the same material as the sleeve 46. In the illustrationshown in FIG. 5, the disc 50 comprises one end of the cartridge 44 whichis considered to be the inlet end, as indicated by the arrow 54. Theperipheral portion 56 of the disc 50, as shown in FIG. 5, is connectedby at least one row of stitches 58 to the peripheral edge portion 60 ofanother disc 62. Enclosed between the discs is a cotton bat 62 oflimited thickness which serves somewhat as an auxiliary filter memberadapted especially to entrap water vapor which may be in gases beingfiltered.

The discs 50 and 61 and the bat 62 sandwiched therebetween somewhatresembles a small pillow. When formed, the peripheral edge portions ofthe connected discs 50 and 61 are secured, preferably by several rows ofstitches 63 to the terminal end portion 63 of sleeve 46, as shown inFIG. 5. After forming the seam comprising the connected peripheralportions 56 of disc 50 and 60 of disc 61, and end portion 63' of sleeve46 by means of the stitches 63, the partially formed sheath is turnedinside out so as to dispose the seam inwardly as shown in FIGS. 3 and 5.The opposite open end of the sheath then is filled with the pulverentfilter material 48. Said other, open end of the sheath then is closed bydisc 52 in the following manner.

The end portion 64 of the sleeve 46 is secured preferably by severalrows of stitches 66 to the peripheral portion 68 of disc 52 as alsoshown in FIG. 4. This forms a seam which initially extends axiallyoutward from the cartridge 44. The terminal end portion 70 and theoutermost portion 72 of the periphery of disc 52 preferably are fused at74 and those portions thereof which extend beyond the stitching 66 insaid seam are then turned inwardly adjacent the outermost row ofstitches 66 and said inturned end portion is secured fixedly in saidposition by an additional row of stitches 76 which extend through allfour plies of the fabric as shown in FIG. 4.

In the illustrations shown particularly in FIGS. 3, 4 and 5, a smallspace has been formed between the adjacent plies of the fabric whichillustrate the seams and other forms of connection between the endportions of the seamless sleeve 46 and the end discs 50, 52 and 61 forpurposes of clearly illustrating the disposition of the various membersof said seams. It will be understood however that such spacings are anexaggeration for clarity of illustration, whereas in actuality, thereare no such spaces and the various plies are in firm abuttingrelationship with each other in said composite seam.

Referring to FIG. 9, an exemplary illustration is shown to illustratethe actual disposition of the seamed end 78 of the cartridge 44 by whichthe end disc 52 is connected to the adjacent end of the sleeve 46. Itwill be seen that rather than said seamed end 78 extending cylindricallyas shown in FIG. 4 with respect to the cartridge 44, it actually isturned inwardly and evenly and firmly abuts the periphery of theadjacent screen. This is due to the fact that the inner surface of thehousing member 12 merges with the seat 20 in the constricted end 26thereof in the form of a relatively smooth curve 80, as shown in FIG. 9.

When the member 14 is removed from the member 12, for purposes ofinserting a new cartridge 44 within the housing 10, the new cartridge isfirst introduced into member 14 and the end of the cartridge whichprojects beyond the outer end of member 14 then is inserted upwardlyinto the interior of member 12. Member 14 is then threaded intoconnection with member 12 and incident thereto, the seamed end 78 of thecartridge will be disposed in the configuration shown in FIG. 9 for thefollowing reasons.

The cartridge 46 when completely formed in the manner described abovehas a length which is slightly greater than the distance between theperforated discs 24 in the opposite ends of the housing 10. Also, theseamless sleeve 46 has a diameter slightly larger than the diameter ofthe interior cavity 38 within housing 10. Accordingly, when thecartridge is inserted within cavity 38 and the member 14 is tightlyconnected threadably with member 12, the filter material within thecartridge 44 is placed under limited pressure which is sufficient toexpand the flexible side walls of the cartridge comprising sleeve 46into firm and circumferentially continuous contact with the innersurfaces of the cavity 38 as well as the ends of the cartridge retainingthe perforated discs 24 firmly against seats 20 and 22 therefore.Accordingly, such firm engagement of the sides of the cartridge 44 withthe walls of the cavity 38 will be maintained at all times during use,whereby no by-passing of gases between the cartridge sleeve 46 and theside walls of the cavity 38 will occur. Accordingly, all fluids, such asgases, and including air, which pass through the filter unit forfiltering by the cartridge 44 will be subjected to filtering action.Therefore, maximum filtering efficiency is insured under thecircumstances.

From the foregoing, it will be seen that the cartridge may be removedfrom, and a new cartridge installed within, the housing 10 easily andquickly. Further, the transparent nature of the housing 10 permitsvisual inspection of the condition of the cartridge at all times,whereby changes in color therein indicate when replacement is necessary.

While the invention has been described and illustrated in its severalpreferred embodiments, it should be understood that the invention is notto be limited to the precise details herein illustrated and describedsince the same may be carried out in other ways falling within the scopeof the invention as illustrated and described.

I claim:

l. A filter unit for gaseous material comprising in combination, ahousing comprising a pair of cupshaped housing members and each havingcylindrical interior wall surfaces of similar length and unifomidiameter, one member having external threads thereon adjacent the openend thereof and the other member having an enlargement at the open endthereof extending outwardly from the interior cylindrical surfacethereof and provided with internal threads complementary to the externalthreads on said one member, whereby the interior wall surfaces of saidmembers when said members are connected defines an elongated cylindricalcavity of uniform diameter extending between the opposite ends of saidhousing, a gasket positioned between abutting end portions of saidmembers when connected together, the opposite end of each of saidmembers being constricted to form seats and also having an axial openingtherethrou'gh of a diameter substantially less than the cylindricalinterior wall surfaces, means on said opposite ends of said membersoperable to be connected to conduit means to feed and discharge gaseousmaterial to and from said housing, perforated discs abutting said seatsin said constricted ends, and a cylindrical filter cartridge within saidcavity in said members when connected together and having a flexibletextile sidewall member slightly larger in diameter than said cavity andalso being slightly longer than the distance between said perforateddiscs, said cartridge being filled with pulverent filter material andthe ends of said cartridge being porous and abutting said discs, saiddiscs being sufficiently rigid to at least slightly compress said filtercartridge axially to force said sidewall member into substantiallycontinuous circumferential engagement with the inner cylindrical cavitywall within said housing members when said members are fully connectedto prevent by-passing of gaseous material between said cavity wall andsaid filter cartridge.

2. "Die filter unit according to claim 1 in which said housing membersare molded from transparent synthetic resin of a rigid type when curedto provide a cylindrical cavity of stable dimensions.

3. The filter unit according to claim 1 in which said housing membersare molded from a polycarbonate resin to render said filter unitsubstantially non-reactive to a wide range of gases capable of beingfiltered by said unit.

4. The filter unit according to claim 1 in which one of said housingmembers has supporting means integrally formed thereon for attachment toa supporting surface.

5. The filter unit according to claim 1 in which said filter cartridgeis provided with a bat of cotton extending across the inlet end of saidcartridge.

6. The filter unit according to claim 1 in which said filter cartridgehas sidewalls comprising a seamless cylindrical sleeve and end discsformed from porous textile material and filled with pulverent filtermaterial, said end discs being secured respectively to the 0pposite endsof said sleeve by stitching, one of said ends having a seam formed bysaid stitching extending into the interior of said cartridge and theother end having a seam formed by said stitching extending outwardly andthe outer end of said seam being turned upon itself and additionallystitched to stabilize said other end of said cartridge.

1. A filter unit for gaseous material comprising in combination, ahousing comprising a pair of cup-shaped housing members and each havingcylindrical interior wall surfaces of similar length and uniformdiameter, one member having external threads thereon adjacent the openend thereof and the other member having an enlargement at the open endthereof extending outwardly from the interior cylindrical surfacethereof and provided with internal threads complementary to the externalthreads on said one member, whereby the interior wall surfaces of saidmembers when said members are connected defines an elongated cylindricalcavity of uniform diameter extending between the opposite ends of saidhousing, a gasket positioned between abutting end portions of saidmembers when connected together, the opposite end of each of saidmembers being constricted to form seats and also having an axial openingtherethrough of a diameter substantially less than the cylindricalinterior wall surfaces, means on said opposite ends of said membersoperable to be connected to conduit means to feed and discharge gaseousmaterial to and from said housing, perforated discs abutting said seatsin said constricted ends, and a cylindrical filter cartridge within saidcavity in said members when connected together and having a flexibletextile sidewall member slightly larger in diameter than said cavity andalso being slightly longer than the distance between said perforateddiscs, said cartridge being filled with pulverent filter material andthe ends of said cartridge being porous and abutting said discs, saiddiscs being sufficiently rigid to at least slightly compress said filtercartridge axially to force said sidewall member into substantiallycontinuous circumferential engagement with the inner cylindrical cavitywall within said housing members when said members are fully connectedto prevent by-passing of gaseous material between said cavity wall andsaid filter cartridge.
 2. The filter unit according to claim 1 in whichsaid housing members are molded from transparent synthetic resin of arigid type when cured to provide a cylindrical cavity of stabledimensions.
 3. The filter unit according to claim 1 in which saidhousing members are molded from a polycarbonate resin to render saidfilter unit substantially non-reactive to a wide range of gases capableof being filtered by said unit.
 4. The filter unit according to claim 1in which one of said housing members has supporting means integrallyformed thereon for attachment to a supporting surface.
 5. The filterunit according to claim 1 in which said filter cartridge is providedwith a bat of cotton extending across the inlet end of said cartridge.6. The filter unit according to claim 1 in which said filter cartridgehas sidewalls comprising a seamless cylindrical sleeve and end discsformed from porous textile material and filled with pulverent filtermaterial, said end discs being secured respectively to the opposite endsof said sleeve by stitching, one of said ends having a seam formed bysaid stitching extending into the interior of said cartridge and theother end having a seam formed by said sTitching extending outwardly andthe outer end of said seam being turned upon itself and additionallystitched to stabilize said other end of said cartridge.